OBJECTIVE: Our goal was to assess the usefulness of helical CT in the presurgical evaluation of hilar cholangiocarcinoma. CONCLUSION: Helical CT aids in tumor localization and in assessment of parenchymal, biliary intrahepatic, and portal involvement in hilar cholangiocarcinoma. However, helical CT is not effective in the assessment of biliary extrahepatic, arterial, and lymph node involvement.